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攀枝花學(xué)院本科畢業(yè)設(shè)計(jì)（論文） 外語文翻譯
攀枝花學(xué)院本科畢業(yè)設(shè)計(jì)（論文）
外文譯文
院 （系）： 機(jī)電工程學(xué)院
專 業(yè)： 機(jī)械設(shè)計(jì)制造及其自動(dòng)化
姓 名： 賀 兵
學(xué) 號(hào)： ZJD02078
指導(dǎo)教師評(píng)語：
簽名：
年 月 日
外語文獻(xiàn)翻譯
原文：
3.4.1CAD HARDWARE
Computers
There are two major types of hardware used in a CAD system. Computer and input/output (I/O) devices. In the early days of CAD. Some commercial CAD systems used proprietary computers. Today, nearly all CAD software runs on a general-purpose computer.
Depending on the complexity of the CAD package, it may require a mainframe computer, a minicomputer, or simply a microcomputer. In general, the more functionalities a CAD system provides, the more powerful the computer needed. Three dimensional solid modelers require much more computing than do two-dimensional drafting systems; thus, they need more powerful computers. Systems that integrate engineering analysis or simulation packages generally are more computation-intensive. A powerful computer not only speeds up the response of a CAD system, but also can support multiple users without significant performance degradation.
Several other parameters and components concerning the computer also have to be considered.
CAD HARDWARE
random-access memory (RAM)capacity
permanent disk-storage capacity
special graphics accelerator
tape backups
RAM is the actual physical memory (vs. virtual memory)of a computer. A small memory capacity means slow processing due to frequent swapping between the physical memory and the virtual memory on disk. Because CAD is extremely storage demanding, disk capacity is important. Small disk capacity limits the system to the storage of only a few drawings. CAD is graphics-based and requires tremendous data processing. A graphics accelerator can drastically increase the performance of the system. Another component, the hard disk, is typically the major cost of a computer system. Therefore, it is not cost-justifiable to store all drawings on line on disk. Magnetic tape is still the most economical medium to use for off-line data storage. It is necessary for a CAD system to have a tape backup subsystem.
Currently, all levels of computers are used in CAD systems. Personal computers are used in low-cost,2-D drafting applications, and with the new power of these computers, hey are also being used for some 3-D solid modeling applications. Engineering workstations have been the mainstay in CAD, and are usually a single-user CAD workstation in a network. Minicomputers are used in multiuser CAD systems. Mainframes are used for large multiuser CAD systems to support real time simulation and engineering analysis. Sometimes, in a large corporation, all levels of CAD systems are implemented. All these systems are linked together through a hierarchical computer network.
3.4.2 Input. Output (I/O)Devices
Figure 3.7 shows the typical I/O devices used in a CAD system. Input devices are generally used to transfer information from a human or storage medium to a computer where ”CAD functions” are carried out. A keyboard is the standard input device used to transmit alphanumeric data to the system. Function keypads are also used to make input easier. Joysticks, track balls, and mousse are also used to manipulate a cursor. They can be used to position the graphic cursor(e.g. cross hair)on a monitor and feed back the location of an object on the monitor to the computer. Using these devices allows an operator to address terminal locations to interactively in reaching an accurate position. Mouses have been used extensively with windows and pull-down menus. They are easy to use for pointing; However, using a mouse to trace a curve is not an easy task.
There are three basic approaches to input an existing drawing;(1)model the object on a drawing,(2)digitize the drawing, or (3)scan the object. Digitizing is usually much easier than modeling. A digitizer is a device that translates the X-Y locations on a drawing than modeling. A digitizer is a device that translates the X-Y locations on a drawing into a digital and feeds that signal to a computer. Graphics scanners scan a drawing and convert it to a CAD-system-readable format. Some scanners have built-in character-recognition software that can convert characters on paper into ASCII codes. Another input device is a sketch pad called a graphics tablet. A graphics tablet is a special flat surface on which a user draws with a stylus. The location of the stylus is sent to the computer. The tablet is an absolute coordinate device. It is easy to implement overlay menus on the tablet and pull down menus on the screen to improve the operation. Currently. the tablet is the most popular input device used in CAD other than the keyboard.
The standard output device for CAD is a monitor display. Modern monitor displays are raster-scan display monitors. Similar to a TV monitor, an electron gun(Sony Trinitron uses three guns for three basic colors)sends an electronic beam to the front of the monitor. Easy display dot is called a pixel(picture element).For color displays, each pixel is represented by three closely located dots with red, green , and blue colors. The electronic beam selects the color elements and the intensity of each color element. The resolution of the monitor is determined by the number of different colors or gray scales displayable at each pixel, usually measured in bits, A 1-bit display can turn each pixel either ON or OFF.A gray scale has at least v2 bits. A 1-bit display can turn each pixel either ON or OFF.A gray scale has at least 2 bits which allow three light intensities plus an OFF (2*2).Usually, displays are 4 bits(16 colors),8 bits(256 colors),16 bits(thousands of colors),and 24bits (millions of colors).The electronic beam sweeps the screen from the top to the bottom line by line. Because the dot is lit for only a very short period of time, the sweep must be done very quickly in order not to have a flickering image. The refresh rate is a measure of how many times the monitor is redrawn in one second.
The computer does not draw directly on the monitor. Connecting the computer to the monitor is u-sually a RGB(red, green, blue)cable. Three separate signal lines are connected. On the graphics board in the computer are circuits to generate the analog signals required to drive the monitor. There is also a frame buffer that serves as memory to store the image. Each pixel on the screen has a corresponding address in the frame buffer. The data in the frame buffer are converted into the appropriate analog signal and sent to the monitor at the refresh rate. Separately, the computer writes directly to the frame buffer the image it intends to draw. The greater the display size and number of colors, the more frame buffer is needed. The frame buffer on the graphics board is made of random-access memory(RAM).
The calculator lend support toes to paint the software AutoCAD to make us can be with the sketch that the astonishing speed draw the engineering sketch or machine sketch and other with accuracy to sophisticate. The calculator paints to paint the different place, one of them with handicraft the paintings with out the diagram divide a step proceed of, because of but would sometimes appear the traditional handicraft the painting hour the problem of the impossible emergence. General circumstance bottom, usage the AutoCAD proceeds painting, control the precision painting and not that difficult, but want accurate then need the certain technique out the diagram. Us-
ually paint or outsing diagram to have no to need to change to measure to AutoCAD system worth make the modification with establish, take its the province worth can normal work, but have the special request, must modify the related system to change measure; Too sometimes the request of the diagram paper with make the diagram's way of doing the antinomy, and be to adopt the to make the diagram method to can't attain the request of the diagram paper, will adopt some techniqueiques to modify the related system to change to measure, and can make the calculator draw to attain the request of the diagram paper with output's sketch.
AutoCAD line type establishing of comparison At teaching of process inside would usually run into what this kind of circumstance, while establishing diagram layer, clearly established the point lin eationed, and consequently output to however investigate its reason for the solid lined, and is usually because of the line typed the establishing of comparison is not appropriate and cau-
sable. Should you so establish the comparison of what kind of line type? How to use the line type the comparison in the painting?
Usage AutoCAD painting, besides continuous line type( Continuous), the other line type is all from the solid line segment, blank segment, point series for or text this constituting. On-line type definition document the inside have already defined these line types the segment's standard length, and show on held the act or at print the machine\ painting output, each length and ex-
portation comparison with line type comparison direct proportion. When show or print, the painting boundary that customer that request, this hour establish is out of accordance with the painting boundary of the province difference big, on held the act show or paint output's line type would match the engineering graphics to will pass the changes line type comparison the system the method that change the deal, enlarge or contract all line types each a small segment of length, make the sketch made meet the request. In the Auto CAD, imply the adjustment line type the comparison's order: Overall situation line type comparison factor tie department exportation ratio for line type ratio factor, used foring the control not continuous line type. The Ltscale is right to have the object validity, Celtscale the province for to new object validating, twoly changing the deal w-
orth all for 1.
For use the line type that Auto CAD2002 painting, big part contain three kinds of forms,( such as: Comparison that Center, Center2, Center*2, Dashed, Dashed2, Dashed*2) the first is a half, the third line type for the standard form, the second line type that comparison that the first line type is the first line type of two times, if line type the comparison establish to is not suitable for, and would then make some exportation diagrams the line( such as the point lineation, dotted line...etc.) change into a solid line.
Two, line breadth the count of establishPass by what handicraft painting, its painting with outs the diagram is a synchronous proceeding of, now calculator painting, its painting with outs the diagram divide a step proceeds. Wether draw the construction engineering diagram or machine spare parts diagram, at print control that a work that exportation engineering drawing, the most is a line to print the drawing the breadth, line the type, color, seal a line breadth for, and eachly growing to line type all contain its cowgirl, in the AutoCAD painting process of the old edition, even defined the line type the width, its at see the diagram area can't also display the line type the width's differentiation.( not contain many righteousness lines the Pline)Width for color for can passing the diagram layer or set upping the line coming distinguish analysing the line.What research of current painting tries a, adopt of is this kind of method.But in the AutoCAD2002, add entity that" Lweight"( line type the width establish) order, provided the new function for customer, then make use of the entity characteristic to proceed the control, and establish the line breadth for the sketch, and make use of it can at hold the act to up show with print to output, control the entity's line breadth.2002 versions inside print to establish and can is divided into three part, and for printing machine belong to the sex to establish, print the style to establish respectively and the page establish.
Because of the model of breadth line the space is different from diagram manifestation of space paper result, in the model space therefore the elephant vegetable show, but in the diagram paper the space is then then to print the width to proceed to show, because of but we while drawing ske tch should know at the diagram line that true width established by line breadth of model space, and is not equal with object. When the line breadth is worth to establish to"0", it show with the minimum width( plain breadth of an elephant) on held the act, and the line breadth settle to other worth, then come showing with the worth specific value of plain width and true unit of elephant.
Three, the sketch output the establishing of comparison When we draw sketch that comparison that comparison output the sketch with us hour use different, can make originally text in the sketch that draw word exportation comparison for marking noting waiting in the output's sketch take placing changing, therefore at drawing the sketch before returning the beard make suring the sketch.For guaranteeing the sketch to output our want the literalness size, should when the text word establish usage following formula: The text word draws the high degree the = the text word output high degree* the sketch to output the comparison; The sketch outputs the comparison= output the diagram the length for of length( width)/ diagram.( width)
draw the width of the diagram line to also should consider this point, its to settle the width same as output the width to multiply by with its comparison worth.
From above practice with analyze to can see out, calculator painting and incompletelyresemble handicraft painting so synchronously paint with out diagram, therefore sometimes make with the diagram method can't attain the request of the diagram paper. Some in common use system that this demand we are deep into control the calculator to paint the theories, and can expertly control the operation method to change the deal with establish the technique, and can make the work of our painting more convenient, smooth, consumedly increase to paint the level with paint the efficiency.
譯文：
3.4.1CAD硬件
計(jì)算機(jī)
兩大主要類型的硬件使用于CAD系統(tǒng)，計(jì)算機(jī)和輸入/輸出設(shè)備。在CAD的早期，一些商業(yè)的CAD系統(tǒng)使用于專業(yè)計(jì)算機(jī)。如今，幾乎全部的CAD軟件都運(yùn)用于普通用途的計(jì)算機(jī)。
根據(jù)CAD命令的復(fù)雜性，它可能需要一臺(tái)大型計(jì)算機(jī)，一臺(tái)迷你型計(jì)算機(jī)，或僅一臺(tái)微型計(jì)算機(jī)，大體上，CAD系統(tǒng)提供更好的功能性，需要更有強(qiáng)的計(jì)算機(jī)。三維空間建模比二維線型建模需要更好的計(jì)算機(jī)；因而，他們需要更有力的計(jì)算機(jī)。那使成整體分析的系統(tǒng)或一般模擬命令是更多更強(qiáng)的計(jì)算。一臺(tái)強(qiáng)的計(jì)算機(jī)不僅加速CAD系統(tǒng)的運(yùn)行，而且也能支持多個(gè)使用者，并不降低使用性能。
幾個(gè)其他的參數(shù)和關(guān)于計(jì)算機(jī)的成分，也不得不被考慮。
隨機(jī)存取儲(chǔ)藏器容量
磁帶容量
專用圖形加速器
磁帶裝置
隨機(jī)存取儲(chǔ)藏器容量是計(jì)算機(jī)的實(shí)際的物理內(nèi)存（相對(duì)，虛擬內(nèi)存）。小的存取容量導(dǎo)致減慢是由于磁盤上的物理內(nèi)存和實(shí)際內(nèi)存的頻繁交換。因?yàn)?，CAD是要求非常大非常多的，磁盤容量是重要的。對(duì)只有一些圖畫的儲(chǔ)藏小磁盤片能力極限系統(tǒng)， CAD是以圖形為基礎(chǔ)的并且需要巨大的數(shù)據(jù)處理，一個(gè)圖形加速器能大幅增加系統(tǒng)的表現(xiàn)。另外的一個(gè)成份 ， 硬盤, 典型地是計(jì)算機(jī)系統(tǒng)的主要費(fèi)用。 因此,它不可置疑的儲(chǔ)藏所有線形圖形到硬盤上。 磁帶仍然是為脫機(jī)的數(shù)據(jù)儲(chǔ)藏使用的最節(jié)儉的媒體。有一卷音帶后緩子系統(tǒng)對(duì)CAD系統(tǒng)是必需的。
現(xiàn)在，所有水平的計(jì)算機(jī)在CAD系統(tǒng)中被用。 個(gè)人計(jì)算機(jī)被用在廉價(jià)的,二維的起草申請(qǐng)中 , 和由于這些計(jì)算機(jī)的新力量 , 他們也被用作在一些三維建模申請(qǐng)。 工程工作站在CAD中有主要的依靠, 和通常在一個(gè)網(wǎng)絡(luò)中是一個(gè)單一使用者CAD工作站.迷你計(jì)算機(jī)在數(shù)字CAD系統(tǒng)中被用。主機(jī)作為大的數(shù)字CAD系統(tǒng)是支援仿真模擬和分析。有時(shí)，在大的公司中，所有水平的CAD系統(tǒng)被實(shí)現(xiàn)。 所有的這些系統(tǒng)通過局域網(wǎng)絡(luò)被一起連接。
3.4.2 輸入/ 輸出 (輸入／輸出) 裝置
圖 3.7 表演在一個(gè)CAD系統(tǒng)中被用的典型輸入／輸出裝置。 輸入裝置通常用來轉(zhuǎn)移來自人或儲(chǔ)藏媒體的數(shù)據(jù)到一部計(jì)算機(jī) "CAD功能" 在哪里實(shí)行。 一個(gè)鍵盤是標(biāo)準(zhǔn)的輸入裝置，過去一直送字母與數(shù)字并用的數(shù)據(jù)到系統(tǒng)。 功能按鍵區(qū)也使輸入更容易。 游戲操縱桿,追蹤球，而且鼠標(biāo)也用來操作光標(biāo)。 他們能用來放置一個(gè)監(jiān)視器上的繪畫似的光標(biāo) ( 舉例來說十字架頭發(fā)) ，而且回饋對(duì)計(jì)算機(jī)在監(jiān)視器上的目標(biāo)位置。使用這些裝置允許一個(gè)操作員交談式在到達(dá)一個(gè)正確的位置方面向終端指出位置。操縱桿和追蹤球在CAD系統(tǒng)中不被廣泛運(yùn)用，由于很難的找到正確的位置。鼠標(biāo)被廣泛地用于窗口和下拉式菜單，他們?yōu)橹赋鍪侨菀资褂玫?然而, 使用一只鼠標(biāo)跟蹤曲線不是一件容易的工作。
有三個(gè)基本接近到輸入一幅已存在的圖畫;(1)一幅圖畫上的物體模型 , 數(shù)字化圖畫 , 或 (3) 掃描物體。 數(shù)字化通常比模型容易。一個(gè)數(shù)字化是進(jìn)入數(shù)傳信號(hào)之內(nèi)在一幅圖畫上翻譯 X- Y 軸位置的裝置和對(duì)一部計(jì)算機(jī)的追蹤信號(hào)。 圖形掃描機(jī)掃描一幅圖畫而且將它轉(zhuǎn)換成CAD系統(tǒng)可讀格式。 一些掃描機(jī)有內(nèi)建的字符識(shí)別軟件進(jìn)入美國信息交換標(biāo)準(zhǔn)代碼密碼之內(nèi)在紙上轉(zhuǎn)換字符。 另外的一個(gè)輸入裝置是一本手抄簿叫做圖形平板。 一個(gè)圖形平板是一個(gè)使用者用鐵筆拉出的特別的平面。鐵筆的位置被派遣去計(jì)算機(jī)。板是一個(gè) 同等的裝置。 實(shí)現(xiàn)平板上的疊菜單而且實(shí)現(xiàn)熒屏上的下拉式菜單改良操作是容易的。 現(xiàn)在，平板是在鍵盤之外的CAD系統(tǒng)中流行的輸入裝置
標(biāo)準(zhǔn)的輸出裝置對(duì)CAD監(jiān)視器顯示?，F(xiàn)代監(jiān)視器是試映圖- 掃描炫耀監(jiān)視器類似一個(gè)電視監(jiān)視器，一個(gè)電子槍 (Sony 單槍三束彩色映像管使用三只槍作為三基本顏色)送電子的光線給監(jiān)視器的前面。 每一個(gè)炫耀點(diǎn)叫做一個(gè)像素 (照片元素) 為彩色顯示，每個(gè)像素三點(diǎn)之間被接近地表現(xiàn)為紅色的，綠色的，和藍(lán)色的顏色。電子的光線選擇彩色元素和每種彩色元素的強(qiáng)度。監(jiān)視器的分辨率被熒屏上炫耀像素的數(shù)量所決定。（像素640*480，1024*1024）
和像素點(diǎn)大?。?4位，32位，等等）。色相和灰度的決議通過不同的色相或灰色刻度決定或開或關(guān)。一個(gè)灰色刻度至少2點(diǎn)允許三種強(qiáng)度光加號(hào)遠(yuǎn)的（2*2）。通常，閃光是4點(diǎn)（16位色），8點(diǎn)（256位色），16點(diǎn)（數(shù)千位色），和24點(diǎn)（數(shù)百萬色）。電子的光線從頂端到線的底線掃除熒屏。因?yàn)楸粸橹挥姓嬲亩虝r(shí)段點(diǎn)亮, 掃除一定被非?？斓匾勒枕樞蜃霾灰幸婚W爍圖像。使比率尺寸是監(jiān)視器在一秒內(nèi)閃爍多少次來衡量。
計(jì)算機(jī)不直接的依賴監(jiān)視器。通常連接計(jì)算機(jī)到監(jiān)視器是 RGB(紅色的，綠色的,藍(lán)色的) 電纜。 三分開信號(hào)線被連接。 在計(jì)算機(jī)中的圖形是產(chǎn)生類比信號(hào)的線路。 也有一個(gè)視為記憶儲(chǔ)存圖像的緩沖。 熒屏上的每個(gè)像素在構(gòu)成緩沖中有一個(gè)相應(yīng)地址。 數(shù)據(jù)在構(gòu)成緩沖中被轉(zhuǎn)換成適當(dāng)?shù)念惐刃盘?hào)并且送給監(jiān)視器在那使比率。分開的，計(jì)算機(jī)直接的寫到構(gòu)成緩沖它想要拉出的像像。顏色的閃耀大小和數(shù)字愈比較很棒, 構(gòu)成緩沖是需要的也愈較多。 圖形上的構(gòu)成緩沖是隨機(jī)存取儲(chǔ)藏器（隨機(jī)存取儲(chǔ)藏器）
AutoCAD的系統(tǒng)變量
計(jì)算機(jī)輔助繪圖軟件AutoCAD使我們能以驚人的速度和精度繪制工程圖形或機(jī)械圖形以及其它復(fù)雜的圖形。計(jì)算機(jī)繪圖與手工繪圖不同之處，其中之一是繪圖與出圖是分步進(jìn)行的，因而有時(shí)會(huì)出現(xiàn)傳統(tǒng)手工繪圖時(shí)不可能出現(xiàn)的問題。一般情況下，使用AutoCAD進(jìn)行繪圖，掌握精確繪圖并不太難，而要準(zhǔn)確出圖則需要一定的技巧。通常繪圖或出圖無需對(duì)AutoCAD系統(tǒng)變量值作修改和設(shè)置，取其缺省值就能正常工作，但有特殊要求時(shí)，就必須修改相關(guān)的系統(tǒng)變量；也有的時(shí)候圖紙的要求與作圖的直觀做法相矛盾，當(dāng)采取直觀作圖法無法達(dá)到圖紙的要求時(shí)，就要采用一些技巧來修改相關(guān)的系統(tǒng)變量，才能使計(jì)算機(jī)繪出和輸出的圖形達(dá)到圖紙的要求。
2.1AutoCAD 線型比例的設(shè)置
在教學(xué)的過程中常常會(huì)碰到這種情況，在設(shè)置圖層時(shí)，明明設(shè)置了點(diǎn)劃線，結(jié)果輸出卻為實(shí)線，究其原因，往往是由于線型比例的設(shè)置不恰當(dāng)引起的。那么應(yīng)該設(shè)置什么樣的線型比例？如何在繪圖中使用線型比例？
????使用AutoCAD繪圖，除連續(xù)線型外，其它線型均由實(shí)線段、空白段、點(diǎn)或文本所構(gòu)成的系列。在線型定義文件中已定義了這些線型段的標(biāo)準(zhǔn)長度，在屏幕上顯示或在打印機(jī)\繪圖儀輸出時(shí)，每一小段長度與輸出比例和線型比例成正比。當(dāng)顯示或打印時(shí)，用戶設(shè)置的繪圖界限與缺省的繪圖界限差別較大時(shí)，在屏幕上顯示或繪圖儀輸出的線型會(huì)不符合工程制圖的要求，這時(shí)就要通過改變線型比例系統(tǒng)變量的方法，來放大或縮小所有線型的每一小段的長度，使所作圖形符合要求。在Auto CAD中，含有調(diào)整線型比例的命令：全局線型比例因子和局部線型比率因子，用于控制非連續(xù)線型的輸出比率。對(duì)所有對(duì)象有效，只對(duì)新對(duì)象有效，兩個(gè)變量的缺省值均為1。
????對(duì)于用Auto CAD2002繪圖，大部分的線型有三種形式, （如：Center、Center2、Center*2，Dashed、 Dashed2、Dashed*2）第一種為標(biāo)準(zhǔn)形，第二種線型的比例是第一種線型的一半，第三種線型的比例是第一種線型的兩倍，如果線型比例設(shè)置不適合，則會(huì)使一些輸出圖線（如點(diǎn)劃線、虛線等）變?yōu)橐粭l實(shí)線。
2.2線寬參數(shù)的設(shè)置
????過去手工繪圖，其繪圖和出圖是同步進(jìn)行的，如今計(jì)算機(jī)繪圖，其繪圖和出圖是分步進(jìn)行的。無論是繪制建筑工程圖還是機(jī)械零件圖，在打印輸出工程圖樣時(shí)，最主要的一項(xiàng)工作是控制打印圖樣的線寬、線型、顏色、封口，且每種線型都有其相應(yīng)的線寬，在舊版本的AutoCAD繪圖過程中，即使定義了線型寬度，其在視圖區(qū)也不能顯示出線型寬度的區(qū)別（不含多義線）。只能通過圖層或設(shè)定線的顏色來區(qū)分線的寬度。目前繪圖員考證的試題，采用的就是這種方法。而在AutoCAD2002中，新增了”Lweight”（線型寬度設(shè)置）命令，為用戶提供了新的功能，即利用實(shí)體特性進(jìn)行控制，為圖形的實(shí)體設(shè)置線寬，利用它可以在屏幕上顯示和打印輸出時(shí)，控制實(shí)體的線寬。2002版中打印設(shè)置可分為三個(gè)部分，分別為打印機(jī)屬性設(shè)置、打印樣式設(shè)置及頁面設(shè)置。
????由于線寬的模型空間和圖紙空間的顯示效果不同，在模型空間是以象素顯示，而在圖紙空間則是以打印寬度進(jìn)行顯示，因而我們?cè)诶L制圖形時(shí)應(yīng)認(rèn)識(shí)到在模型空間由線寬設(shè)置的圖線，與對(duì)象的真實(shí)寬度并不相等。當(dāng)線寬值設(shè)為“0”時(shí)，它在屏幕上以最小的寬度（一個(gè)象素寬）顯示，線寬定為其它值時(shí)，則以象素寬度與真實(shí)單位值的比值來顯示。
2.3圖形輸出比例的設(shè)置
當(dāng)我們繪制圖形的比例與我們輸出圖形時(shí)使用的比例不同時(shí)，就會(huì)使原來繪制的圖形中的文字標(biāo)注等在輸出的圖形中發(fā)生變化，因此在繪制圖形之前還須確定圖形的輸出比例。為了保證圖形輸出時(shí)文字的大小是我們所想要的，應(yīng)在文字建立時(shí)使用如下公式：文字繪制高度=文字輸出高度*圖形輸出比例；圖形輸出比例=輸出圖幅的長度（寬度）/圖幅的長度（寬度）。
同理，繪制圖線的寬度也應(yīng)該考慮這點(diǎn)，其給定寬度等于輸出寬度乘以其比例值。
????從以上實(shí)踐和分析可看出，計(jì)算機(jī)繪圖并不完全像手工繪圖那樣同步繪圖和出圖，因此有時(shí)用直觀作圖法無法達(dá)到圖紙的要求。這就需要我們深入掌握計(jì)算機(jī)繪圖理論，并能熟練地掌握一些常用的系統(tǒng)變量的使用方法和設(shè)置技巧，才能使我們的繪圖工作更為便利、順暢，大大地提高繪圖水平和繪圖效率。
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